HR: 0830h
AN: G21D-0289    [PDF]
TI: Distribution of Displacement Across Canyonlands Grabens Using GPS and InSAR
AU: * Marsic, S D
EM: marsic@usc.edu
AF: University of Southern Califoria, Department of Earth Sciences, Los Angeles, CA 90089 United States
AU: Owen, S E
EM: owen@usc.edu
AF: University of Southern Califoria, Department of Earth Sciences, Los Angeles, CA 90089 United States
AU: Crider, J G
EM: criderj@cc.wwu.edu
AF: Western Washington University, 516 High Street, MS 9080, Bellingham, WA 98225 United States
AB: The Needles District of Canyonlands National Park in southeastern Utah is a unique geologic region in which active extensional salt tectonics can be observed. The Needles District of the Canyonlands consists of an approximately 500-meter-thick sedimentary section that is underlain by the Paradox evaporites. This entire package is situated on the western flank of the Monument Uplift. As the adjacent Colorado River incised down into the Paradox salt substrate, the upper sedimentary sequence became unbuttressed and consequently begain to extend toward the Colorado River along the $4\deg$ northwest dip of the Monument Uplift's western flank. Prior to our study, knowledge of Canyonlands deformation rates was limited to long term geologic averages between 2 mm/yr and 2 cm/yr that assumed spatial and temporal uniformity. Our research utilizes two geodetic techniques, Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR), to observe a clearer picture of current deformation rates across the entire study area. Rates from these two techniques are independently determined, thereby allowing a means of comparison and error estimation. Utilizing 14 European Remote Sensing (ERS) Synthetic Aperture Radar (SAR) images encompassing a 7-year period of observation (1992-1999), 10 successful interferograms with short baselines ($<$ 100 m) from both ascending and descending orbital trajectories have been produced. The decomposition of these interferograms, in conjunction with campaign GPS data, indicates relative regional subsidence of up to 3 mm/yr within the graben system, predominantly east of Cataract Canyon. The interferograms additionally show spatially varied rates of horizontal deformation, with a maximum rate of deformation (6 mm/yr) near the eastern margin of the faulted region. GPS observations corroborate InSAR decomposition results. Observations of deformation along several profiles support prior modeling efforts that suggest basal salt flow regulates overburden deformation.
DE: 1208 Crustal movements--intraplate (8110)
DE: 1242 Seismic deformations (7205)
DE: 1243 Space geodetic surveys
DE: 1294 Instruments and techniques
DE: 1709 Geodesy
SC: Geodesy [G]
MN: 2003 Fall Meeting